Ignition control means



April 1, 1941 v SQDERHQLM 2,237,120

IGNITION CONTROL MEANS Filed Jan. 3, 1938 loses.

0n heai'mg 54 and 55 closes before 45 and 46 opens- On coolmg 54 and 55o ens beForG 45and 46c a. .2 :3 9 INVENTOR 3 Laurenusoderholm m a, 5! BYg #M R ATT RNEY Patented Apr. 1, 1941 rem'rron comor. mums Lauren V.Soderholm, Minneapolis, Minn, assignor to.

Minneapolis-Honeywell Regulatorv Company, Minneapolis, Minn, acorporation of Delaware Application January s, 1938, Serial No. 183,020llfilaims. (Cl. 158- 128) This invention relates to a switching means ingeneral and to the combination of this switching means in an oil burnercontrol system for controlling the ignition thereof.

Ignition switches have long been provided for turning on and ed theignition oi an oil burner apparatus, but it has been found necessary inthe past to utilize two switches connected in series for this purpose,one beingoperated upon the starting of the oil burner apparatus to startthe ignition and the other being operated upon the establishment ofcombustion to stop the ignition.

"The 'use of two switches for accomplishing this result necessarilyincreases the cost of an oil burner control system.. Also the switch.that is operated by the combustion responsive device carries relativelyhigh currents and must either be of the mercury switch type or if opencontact, it must be of-the snap action type. Either of these types ofswitches require a relatively large amount of work by the combustionresponsive device for operating the same which is diflicult to obtainand still keep the cost and size of the combustion responsive devicewithin reasonable limits.

It is therefore the prime object of this invention to eliminate theabove difllculties by providing a new and novel switching mechanism forcontrolling the ignition oi an-oil burner apparatus.

In carrying out this invention a single switch is utilized for turnng onthe ignition means when the oil burner apparatus is. placed in operationand for turning oil the ignition means when combustion is established.Also this switch is closed when the oil burner apparatus is placed inoperation by means of the main operating relay which has comparativelyunlimited power and the switch is opened upon the establishment ofcombustion by having the combustion responsive device merely release alatch which requires only a relatively small amount of work.

Accordingly, an object of this invention is to provide a single switchfor controlling the operation of the ignition of an oil burnerapparatus.

Another object of this invention is to operate this switch by-the mainrelay of the oil burner control system which has relatively unlimitedpower and to release the switch by the combustion responsive device withthe expenditure of a minimum amount of eiTort thereby.

A further object of this invention is to provide a new and novelswitching mechanism.

Other objects and advantages will become apparent to those skilled inthe art upon reference to the accompanying specification, claims anddrawing in which:

Figure l is a vertical sectional view of the combustion responsivedevice taken substantially along the line i-l-of Figure 2; v Figure 2 isan end elevational view of the combustion responsive device lookingtoward the left in Figure 1 and also an elevational view of the mainoperating relay;

Figure 3 is a sectional view of aporticn of the combustion responsivedevice illustrated in Figures 1 and 2 and taken substantially along theline 3-3 of Figure 2;

Figure 4 is a side elevational view ofthe main operating relay showingthe relay energized and the ignition switch closed;

Figure 5 is a side elevational view of the main operating relay showingthe relay energized and the ignition switch opened; and.

Figure 6 is a schematic wiring diagram of the oil burner control systemof this invention.

Referring now to Figure 1, the combustion control device is generallydesignated at H) and is shown to comprise a mounting member ii ,to whichis secured a tube l2 which is adapted to extend into the combustionchamber or into a stack through which the gases of combustion pass. Oneend of a bimetallic element i3 re sponsive to combustion temperatures issecured to the tube l2 and the other end is connected to:

a rod it which extends concentrically through the tube It. The rod i4 isjournaled in a bearing i5 and is connected to a connecting member ii. A

spring it tends to urge the connecting member i8 and hence the rod i4towards the right. Upon a decrease in combustion temperature afiectingthe bimetallic element i3, the rod l4 and connecting member I6 are movedto the left against the action of the spring l1 and upon an increase intemperature they are moved to the right in the direction indicated bythe character H.

An operating rod i8 is suitably secured to the connecting member i6 andextends through an opening N in a base 20 preferably made of insulatingmaterial and suitably connected to the mounting member II. The rod l8isiprovided with a circumferentially grooved portion 2| which extendsoutwardlybetween brackets 26 and I suitably secured to the base 20. Thebrackets 24 and 25 are provided with pins 28 and 21, and upon these pinsare mounted switch operating -members and 50, respectively.

Referring now to Figure 3, the switch operating member 30 is shown tocomprise arms 28 and 29 pivotally mounted on the pin 26. Abutting thearms 28 and 29 are friction washers 3| and 32 and abutting thesefrictionwashers are operating members 33 and 34 formed with grooves which engagethe grooves of the grooved member 2| of the rod I8. A spring 35 isinterposed between the operating members 33 and 34 so that the operatingmembers are frictionally coupled to the arms 28 and 29 of the switchoperating member 30. Upon an increase in combustion temperatureaffecting the bimetallic element l3, the

rod I8 is moved to the right as viewed in Figure 1 and the switchoperating member 38 is moved in a counter-clockwise direction as viewedin Figure 1, and upon a decrease in temperature the rod I8 is moved tothe left to cause clockwise movement of the switch operating member 30.The switch operating member 30 is provided with an extension 38 which isadapted to engage spaced stops 39 to limit the amount of rotation base20. A spring 633 maintains the follower it in engagement with the switchoperating member 30. The lever ll carries an arm 46 which in turn Icarries a contact 65 adapted to engage a-stationary contact 65 carriedby' a bracket 4W suitably secured to the base 20. Upon a decrease intemperature which causes clockwise rotation of the switch operatingmember 38, the contact 65 is moved into engagement with contact 65 andupon an increasein temperature which causes counterclockwise rotation ofswitch operating member .30, contact 65 moves out of engagement withcon- .tact 36. The contacts 435 and 46 form what are commonly termedcold contacts.

The switch operating member 55 is operated by grooved operating members5| and 52 in exactly the same manner as the switch operating member 30is operated, and therefore a further description of this portion of thedevice is not considered necessary. carries an arm f53-upon which ismounted a contact 56. The contact 541 is adapted to engage a stationarycontact 55 carried by a bracket 56 suitably secured to thebase 20. Astop 57 also secured to the base limits counter-clockwise rotation ofthe switch operating member 50; Upon an increase in temperatureaffecting :the thermostatic element I3, the switch operating member 50is'moved in a clockwise direction as viewed in Figure 1 to move thecontact 56 into. engagement with contact 55, and upon a decrease intemperature the switch operating member 50 is moved in acounter-clockwise direction into engagement with stop 51 to separate thecontacts 54 and 55. The contacts 54 and 55 form what are commonly termedhot contacts.

,The parts thus far described are so arranged that with the thermostaticelement l3 cold, as

when .combustion is not present, the contact 45 is engaging the contact46 and the contact operating member 50 is in an extremecounter-clockwise position against the stop 51 to maintain the contacts54 and 55'separated, Upon the establishment'of combustion, thethermostatic element I3 heats up to move the rod l8 toward he right Theswitch operating member 50 which first causes engag ment of the contacts54 and 55 and then separates the contacts and 46.

When combustion is stopped and the thermostatic element i3 cools,contacts 56 and are first separated and then contact 45 is moved intoengagement with contact 46. In other words, upon an increase intemperature the switching actions of the contacts 54 and 55 and thecontacts and to overlap, while upon cooling the switching actions do notoverlap.

Referring now to Figures 2, 4, and 5, the main operating relay is shownto comprise a core 6| suitably secured to the base 20 and having anoperating coil 62. An armature 53 pivoted at 64 to an extension 65 ofthe core 6| is attracted toward the core upon energization of the coil62. The armature 63 carries an insulating member 56 to which issecured,an arm 61 carrying a contact 68 which is adapted to engage a contact 69carried by a'stationary bracket 10 when the operating coil 82 isenergized. The insulating member 63 also carries an arm II (Figure 2) towhich is secured a contact 12 which is also adapted to engage a contactI3 carried bya bracket 1% when the operating coil G2 is,energized. Thecontacts TI and 72 form a load switch for the burner motor, while thecontacts 68 and 69 form a maintaining switch for the operating coil 52of the relay.

The insulating member 66 also carries an arm 78 upon which is mounted abracket l9 carrying a pin 86. A contact member 8| is pivotally mountedon the pin 80 and isbiased in a counterclockwise direction, as viewed inFigures 4 and 5, by a spring 82. Counter-clockwise movement of thecontact member BI is limited by an adjustable stop 83 suitably securedto a bracket 84. When the spring 32 is overcome in a manner to bepointed out immediately hereafter, the contact member 8| engages acontact 85 carried by a bracket 85 when the operating coil 62 of therelay is energized. The contact arm 8| and the contact 85 form anignition switch for controlling an ignition means.

In order to overcome the spring 82, the contact arm 8| is provided withan extension 81 carrying a pin 88 which is engaged by an inner surfaceon a cam member 89 mounted on the pin 26, as shown'in Figure 4.Accordingly, when the pin 88 engages the inner surface 90 as shown inFigure 4, the pivotal connection between the contact arm BI and the arm78 is maintained relatively rigid'so that the contact arm 8| is movedinto engagement with the contact 85 when the operating coil 62' of therelay is energized. The cam means 89 is provided with an opening 9|which when moved adjacent the pin 88 allows the spring 82 to move thecontact arm 8| in a counter-clockwise direction to disengage the contactarm 8| from the contact 85, even though the relay coil 62 is energizedas shown in Figure-5. The position of the cam means 89 is controlled byan arm 92 carried by the switch operating member 30. When combustion isnot present, the cam means 89 assumes the position shown in Figured tomaintain the connection between the arm 78 and the contact arm 3|substantially rigid so that the contact arm 8| is moved into engagementwith contact 85 when the operating coil 62 is energized. -Whencombustion is established, the cam means 89 is moved by the arm 92 in aclockwise direction, as viewed in Figures 4 and 5, to align the opening9| of the cam" means 89 with the'pin '88 whereupon the pin 88 isreleasedto allow the spring means 82 to move the contact arm 8| out ofengagement with the contact 85. This operation occurs at substancontact46.

out of engagement When the relay coil 62 is deenergized while the partsare in the position shown in Figure the armature 63 will drop out eventhough the contact arm 8| is engaging the stop 83 and the spring82 istending to hold the armature 63 in. This is due to thefact that spring82 is quite weak and although it is strong enough to break 7 contactsflland 85 after combustion has been established, it is not strong enough toprevent armature 63 from dropping out when the coil 62 is deenergized.When the armature 63 drops out and the contact arm 8i is engaging thestop 83 .the pin 83 will move inwardly oi the cam means 89 sothat whenthe thermostatic element it decreases in temperature the cam means 823may rotate in a counter-clockwise direction to cause the inner surface Wto engage the pin 88. In'this manner the connection between the arm l8and the contact arm 88 is made substantially rigid as shown in Figure 4preparatory to the next cycle of operation.

' Referring now to the schematic wiring diagram of Figure 6, a spacethermostat is generally designated at 95 and may comprise a thermostaticelement 95 for operating switch arms iii and 99 with respect tostationary contacts 98 and its. The contacts are so arranged that upon adecrease in space temperature the switch arm 51 first engages thecontact 93 at, S y 72, and theswitch arm as next engages the contacttilt, at, say 70". The oil burner motor is designated at Hi2 and theignition means therefor is designated at W3. A safety switch isgenerally designated at it? and may comprise a thermostatic element i336adapted to engage a contact it? and adapted to be heated by a heaterelement lot. When the heater element 598 is an ergized, the thermostaticelement M36 is moved to the right after a predetermined length of timeto disengage the contact Hill.

The relay in Figure 6 is shown to comprise the operating coil 52, themaintaining switch formed by arm ti and contacts 68 and tihand theburner switch formed by arm ii and contacts i2 and it. The combustionresponsive device generally designated at ill shows the contacts 65 and66 forming the cold contacts, the contacts 5 3 and 55 forming the hotcontacts and the contact arm 8i andthe stationary contact 85 forming theignition 'switch. Power is supplied to the control system by vmeans of astep-down transformer its having a secondary iii and a primary H2connected across line wires lid and ti l leading from some source ofpower (not shown).

Assume now that the space thermostat is satisfied, accordingly the relayis dropped out, the burner motor W2 and. the ignition means its aredeenergized and the cold contacts 65 and d6 are closed. When thetemperature ate footing the thermostat 95 decreases to '30 so as to makecontacts 99 and Hill, a starting circuit is completed from the secondaryiii through contact 98, switch arms 97' and 89, contact int. operatingcoil 52, cold contacts 4325 and as, heater element 098, thermostaticelement its, and contact ill! of the safety switch Hi5 bacls to thesecondary iii. Completion of this starting circuit energizes theoperating coil 62 to pull in the relays When the relay is pulled in,contact 68 engages contact 69, contact 12 "engages contact l3, andcontact arm 8i engages contact arm 1!, and burner motor I02 back to theother line wire H4. In this manner the burner motor is operated.Movement of the contact arm 8! into engagement with the contact 85completes an ignition circuit which may be traced from the line wire iiithrough contact arm 8i, contact 85 and ignition means its back to theline wire lid. In this manner the ignition means is energizedsimultaneously with the placing in operation of the burner motor W2.

Movement of the contact 88 into engagement with contact 69 completes amaintaining circuit for the operating coil 52 oi the relay which may betraced fromthe secondary iii through contact 38, switch arm ill,thermostatic element 96. contact 89, contact 68, switch arm iii,operating coil 62, cold contacts iii and to, heating element 7 Hit,thermostatic element Hi6 and contact iill back to the secondary Hi. Thiscircuit will maintain the operating coil 62 energized and hence therelay pulled in even though the temperature should rise above 70.

If upon operation of the burner motor m2 and the ignition means 962]combustion is not established within a predetermined length of time. theheater element m8 will flex the thermostatic element tee of the safetyswitch to the right to disengage the contact till! thereby breaking boththe starting and maintaining circuits outlined above to drop out therelay and cause shutting down oi the burner motor Hi2 and the ignitionmeans M353. If, on the'other hand, combustion is successfullyestablished the thermostatic element it or" the com-hustion responsivedevice it heats up and moves the contact 86 into engagement with contact55 to complete a running circult for the operating coil 82 which may betraced from the secondary iii through contact 98, switch arm 9?,thermostatic element @6, con= tact 99, contact 66, contact arm 67?,operating coil 02, hot contacts 56 and 65, thermostatic element 6%, andcontact it)?! back to the secondary iii. Completion of this runningcircuit shunts out the heating element its oi the safety switch 6% whichmaintains the relay energized and hence the hurner motor tilt running.Since contact 50 engages contact 55 before contact 36 disengages contact65, the circuits throughthe operating coil $2 of the relay are notinterrupted and continuous'action is assured.

At substantially the same time the contact moves out oi engagement withthe contact (it, the c means 89 releases the pin 88 to cause the"contact arm to move out of engagement paratus wherein only a singleignition switch is utilized for turning on and turning oil the igni=tion means at predetermined points in the cycle of operation oi the oilburner apparatus, wherein the ignition switch is operated primarily bythe relay which has a relatively unlimited amount of power, and whereinthe ignition switch is opened by the combustion responsive device bymerely tripping a latchwith a minimum amount of effort.

Although for purposes of illustration I have shown one form of thisinvention, other forms thereof may become apparent to those skilled inthe art upon reference to this disclosure and therefore this inventionis to be limited only by the scope of the appended claims and prior art.

I claim as my invention:

1. In a control system for an oil burner apparatus having burner meansand ignition means, the combination of, a relay having a burner switchoperatively associated with the burner means and an operating coil toclose the burner switch when energized for operating the burner means,an ignition switch comprising a stationary contact and a movable contactoperatively associated with the ignition means, a member operated by therelay coil of the relay, a direct mechanical connection between themember and the movable contact of the ignition switch, biasing meansincluded in the connection for biasing the movable contact of theignition switch to an open position, an abutment member carried by themovable contact of the'ignition switch, cam means engaging the abutmentmember and operating to overcome the biasing means so that the ignitionswitch is closed upon energization of-the operating coil of the relay,and means operated as an incident to establishment of com-- bustion foroperating the cam means to disengage the cam means and the abutmentmember whereupon said biasing means opens the ignition switch to stopoperation of the ignition means.

2. A switching means for controlling the operation of an ignition meansof an oil burner apparatus, comprising in combination, an electromagnet,a member operated thereby, a switch comprising a stationary contact anda movable contact, a resilient connection between the member and themovable contact of the switch, latch the stop.

5. In combination, aswitch having a stationary contact and a movablecontact, an electromagnet, a member operated by the electromagnet, aresilient connection'bet'ween the member and the movable contact of theswitch acting to open the switch, latch means associated with theresilient connection to maintain the same rela- Y tively rigid, thearrangement being such that the switch is closed and opened uponenergization and deenergization of the electromagnet, conditionresponsive means, and means including a slip friction connection betweenthe condition responsive means and the latch means for releasing thelatch means when the condition has changed a predetermined amount toallow the resilient connection to open the switch.

6. A control system for a fuel burning device, comprising incombination, electrical fuel feed control means, means for igniting thefuel, a first switch in control of said fuel feed control means, asecond switch in control of said ignition means, means forsimultaneously closing ,said first and second switches, a connectionbetween said last named means and said second switch, said connectionrequiring support in order to render it operative to close said secondswitch, and combustion responsive means providing such support in theabsence of combustion and for mechanically removing said support topermit said second switch to open upon the establishment of combustion,and slip friction means between said combustion responsive means andsaid support;

means associated with the resilient connection 7. An ignition controlfor a fuel burner com prising in combination, a biased open ignitionswitch, an electromagnet, connections between said electromagnet andsaid switch, a stop having a first position in which it cooperates withsaid switch to render it capable of being closed by said electromagnetand connections-upon enerfor releasing the latch means to cause theresil.-

ient connection to open the switch contacts for stopping operation ofthe ignition means. i

3. In combination, a switch comprising a stationary contact and amovable contact, an electromagnet, a member operated by theelectromagnet, a resilient connection between the member and the movablecontact of the switch acting to open the switch, latch means associatedwith the resilient connection to maintain the same relatively rigid,.thearrangement being such that the switch is closed and opened uponenergization and deenergization of the electromagnet, and conditionresponsive means for releasing the latch means to allow the resilientconnection to open the switch. 4. In combination, a movable contact arm,a stationary contact on one side of the arm and adapted to be-engagedthereby, a stop on the other side of the arm and adapted tobe engagedthereby, resilient means for biasing the movable contact arm away fromthe stationary contact toward the stop, an electromagnet, a memberoperated thereby, a pivotal connection between the member and themovable contact arm, releasable means for overcoming the resilient meansand for holding the arm and member relatively fixed with respect to eachother so that gization of said electromagnet, and combustion responsivemeans for mechanically removing said stop to permit said switch to opendue to its bias, and slip friction means between said combustionresponsive means and said stop.

8. A control system for fuel burners comprising in combination, anelectrical fuel feeding device, a control switch therefor, an ignitiondevice, a biased open ignition'switch therefor in cluding a movablymounted switch arm, an abutment member having a first position in whichit restricts the movement of one portion of said arm, a relay forsimultaneously closing said switches, the closing of said ignitionswitch being dependent upon the abutment member being in said firstposition to restrict the movement ing in combination, an electrical fuelfeeding device, a control switch therefor, an ignition device, anignition switch comprising a first contact and a movable contactcarrying arm biased to open position, a relay for simultaneously closarmand permit it to move ing said control switch and ignition, switch, anabutment, a portion of said movable contact arm reacting against saidabutment to overcome the effect of said bias and render said relayoperative to close said ignition switch, a thermal element responsive tocombustion, and mechanical connections between said thermal element andabutment whereby said abutment is moved directly by the force developedin said thermal element as a result of the establishment of combustionto move said abutment and release said movable contact to open contactposition under the influence of its bias.

10. A control system for a fuel burning device comprising incombination, electrical fuel feed control means, means for igniting thefuel, a first switch, said fuel feed control means being under the solecontrol of saidflrst switch, a second switch in control of said ignitionmeans, an electromagnet for closing saidfirst and second switches, athermal safety switch, a heater therefor, a thermal element responsiveto combustion of the fuel, hot and cold switches mechanically actuatedby said combustion responsive element, a main switch closing a circuitincluding said safety switch, the heater therefor, the cold combustionswitch and the electromagnet, said electromagnet closing said first andsecond switches to initiate combustion, said combustion respon- 5 siveelement first closing said hot switch to shunt the safety switch heaterand then opening said cold switch, and mechanical connections betweensaid element and second switch for tripping said second switch to openposition, said combustion responsive element first opening said hotswitch following a flame failure to deenergize the electromagnet andshut the system down and then reclose the cold switch to cause thesystem to recycle.

11. A control system for fuel burners comprising in combination, anelectrical fuel feeding device, a control switch therefor, an ignitiondevice, an ignition switch comprising a first contact and a movablecontact carrying arm biased to open position, a relay for simultaneouslyclosing said control switch and ignition switch, an abutment, a portionof said movable contact arm reacting against said abutment to overcomethe efiect of said bigs and render said relay operative to close saidignition switch, and thermal means rendered active for automaticallymoving said abutment to release said movable contact arm and permit itto move to open contact position under the influence of its bias aftersaid electrical fuel feeding device has been energized and combustionestablished.

LAUREN V. SODERHOLM.

